Open main menu

Watt-hour per kilogram

The watt-hour per kilogram (SI abbreviation: W⋅h/kg) is a unit of specific energy commonly used to measure the density of energy in batteries and capacitors. One watt-hour per kilogram is equal to 3600 joules per kilogram.

Typical valuesEdit

The batteries that Tesla uses in their electric cars have about 254 W⋅h/kg [1], compared to supercapacitors that are typically between 3-10 W⋅h/kg [2], albeit with research ongoing into enabling much higher values.


  1. ^ "Tesla’s batteries have reached their limit – here’s how they could go further",, 2017-11-16
  2. ^ Hao Y, Santhakumar K. "Achieving Both High Power and Energy Density in Electrochemical Supercapacitors with Nanoporous Graphene Materials" (PDF): 3. Retrieved 2017-11-16.